In certain building and office structures, it is advantageous to supply air conditioning by way of a raised floor structure forming an under floor plenum. By way of openings provided selectively in the flooring elements, the air conditioning flows are controllably directed into the room space or spaces above the floor. Such arrangements are widely employed in data centers, for example, but are also usefully employed to provide air conditioning on a controllable and efficient basis to modern offices.
Computers and related equipment utilized in offices, business, industry, government telecommunications, the internet, data storage facilities, and the like quite commonly are located in great numbers in dedicated buildings or dedicated areas of buildings, in which the equipment is arranged in relatively high density configuration, in racks, for example, for convenient supervision and maintenance. A common practice in connection with such high density data centers is to provide a raised floor structure made up of individual floor tiles supported on a suitable skeletal framework, providing a convenient plenum space underneath for the passage of cooling air and the necessary data and power cables. Suitable cable cut-outs or openings are provided in the floor tiles to accommodate the passage of the power and data cables from the space underneath the floor upward for connection to the computer units within the room above. Typically, large numbers of such cable openings are provided. For example, there may well be as many as sixty cable openings (of a typical size of about 4xe2x80x3xc3x978xe2x80x3) per thousand square feet of floor space.
Because the set up and operation of the computer equipment within a large data center can be very dynamic, in order to accommodate the rapid growth and change within the industries served, it is necessary not only to have relatively large numbers of grommet openings, but also that they be conveniently accessed and used in order to facilitate frequent re-routing of power and data cables.
In the operation of high density data centers, significant heat is generated by the operating units, and it is necessary to provide suitable air conditioning in order to maintain the equipment at a suitable operating temperature. Conventionally, the necessary air conditioning is provided by discharging cool air into the cable space provided below the elevated floor structure. Selected perforated floor tiles, provided with a desired pattern of openings, are appropriately positioned in relation to the operating units, sometimes directly beneath, and sometimes alongside, arranged to discharge cooled air upwardly, where the air may be drawn into the operating units by their internal fans.
The air conditioning of the operating units is complicated significantly by the presence of large numbers of cable openings throughout the floor space. Large quantities of the cool air escape through these large openings into the general ambient of the room, where the cool air cannot be efficiently utilized. The escape of conditioned air through the cable openings can be such as to reduce the static pressure in the cable space underneath the floor from a desired 0.10xe2x80x3 of water, for example, to as little as 0.01xe2x80x3. While this xe2x80x9clostxe2x80x9d cooling air does enter the ambient space of the data center, it is not effectively and efficiently available to be drawn into the operating units, and often simply mixes with hot air being discharged from the operating units by their internal cooling fans. The loss of efficiency can be as great as the equivalent of a 20 ton cooling unit for each thousand square feet of computer room floor space.
Some attempts have been made to reduce the loss of conditioned air through floor openings, by stuffing the openings with foam pads, rags, small pillows, etc. These have been haphazard at best and generally of minimal usefulness.
In a similar manner, controlled air conditioning of modern office space is sometimes accomplished by providing the conditioned air via an under floor plenum associated with a swirled diffuser supply system, with selectively located under floor diffusers and floor grates to provide for controlled upward discharge of the conditioned air into the office space. Such arrangements often seek to increase efficiency by providing for a swirling action of the discharged air, a technique that tends to provide for equivalent comfort levels while maintaining the ambient temperature at least slightly higher than otherwise, to achieve greater air conditioning efficiencies. For such systems, uncontrolled leakage of conditioned air through cable openings and the like provided in the flooring can reduce the operating efficiencies of the system, and a need is indicated for efficient means for sealing such openings.
The present invention relates to a novel and improved form of floor grommet for use in large, high density data centers, under floor office air conditioning and the like, which substantially seals off the cable openings around the power and data cables or other elements passing therethrough. There is thus a minimal loss of cooling air through the multiple cable openings and a maximized flow of such air is directed through the intended discharge openings, e.g., adjacent to and/or underneath the operating units, or through special outlets to provide a desired swirling action. In a particularly preferred embodiment of the invention, a standard cable opening of 4xe2x80x3xc3x978xe2x80x3 or 5xe2x80x3xc3x978xe2x80x3 dimensions is xe2x80x9csealedxe2x80x9d by a plurality of thin filamentary elements extending from opposite sides of a grommet frame and meeting in the central area of the grommet opening. The density of these filamentary elements is such that power and data cables may be easily threaded through the grommet opening by displacement of the elements, which then largely close around the cables to minimize any opening for the escape of conditioned air. To a particular advantage, the filamentary elements may be provided by brush-like bristle assemblies, formed of relatively fine bristles of materials such as nylon, polypropylene or natural horsehair.
In a particularly advantageous form of the invention, a plurality of layers of the bristle assemblies of different lengths and configurations are provided within a grommet frame. A first layer of opposed bristles extends from one side of the grommet frame, meeting in the center of the grommet opening. A second layer of bristles is disposed directly below the first, and advantageously consists of bristles of a somewhat shorter length which do not extend completely to the center of the grommet opening. Advantageously, the two levels of bristles are disposed so that the shorter bristles and the longer bristles are in contact in their outer areas.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of preferred embodiment to the invention and to the accompanying drawings.